One Windows is simply not enough! Call US +1 877 734 6106 to find out Call UK 0800 027 2002 to find out HyerDrive IV (large) backup battery   Specification Features: High capacity Li-Ion battery 7.4 V 9600mAh made of 8pcs matched LG 18650 2400mAh Li-Ion cylindral cells with 4 PCB inside. Light weight and compact size. Much smaller than NiMH battery pack. One set of detachable universal connectors with 6 plug tips is included and will fit most of DC devices. One multi voltage smart Li-Ion battery charger is included for safely charging. Auto cut off power when battery is full charge. You just plug it in and leave it. Double PVC shrink wrap for water resistant Perfect for 6V Halogen bike upto 35 W Can run 20W max. Halogen light, burntime is 3.5 hours Perfect for super-bright bike headlight of 6 -35W. Can replace any 6V NiMH battery or 7.2V Li-Ion Specifications for Li-Ion Battery Pack: 8 pcs High quality Li-Ion cyclindral cells 2400mAh : 2 series and 4 paraarallel Two PCB IC inside to protect over charger and discharger Voltage: 7.4V Capacity: 9600mAh (71 Wh) Dimension: 40 (W) x 40 (H) x 70 (L) mm Weight: 13.5 Oz Max. discharging rate: 6 A Recharged Cycles: > 500 times 5" cable with a femal universal connecor Burning time: 5W Halegon: 14 hrs 10W Halogen: 7 hrs 20w Halogen: 3 hrs Specifications for Smart Charger In-put: AC 100 -240V Out-put: DC 8.4V, 1000mA Cut off automaically if battery full In Charging --- Red LED Battery Full --- Green LED 40 W x 15 H x 92 mm L 4' detachable power cable Extra 5' cable with femal connector for link to your lighting system 8 pcs plug tip with various diameter ( O.D.) 6.02 mm , 6.29 mm, 5.47 mm, 5.48 mm, 5.45 mm, 5.01mm, 4.75 mm, 3.98mm